Michael
If you live close to a LDS Family History Centre. They have the Burnt Records of the British Army WW1.
I have edited this from the search for you entering by "British Army" on the LDS site:Title search by title
British Army
Military records of the British Army, 1914-1920 (surnames A-E) : Great Britain. War Office
Military records of the British Army, 1914-1920 (surnames F) Great Britain. War Office
Military records of the British Army, 1914-1920 (surnames G-I) : Great Britain. War Office
Military records of the British Army, 1914-1920 (surnames J-K) : Great Britain. War Office
Military records of the British Army, 1914-1920 (surnames L-M) : Great Britain. War Office
Military records of the British Army, 1914-1920 (surnames N-O, Q) : Great Britain. War Office
Military records of the British Army, 1914-1920 (surnames P) : Great Britain. War Office
Military records of the British Army, 1914-1920 (surnames R) Great Britain. War Office
Military records of the British Army, 1914-1920 (surnames S) Great Britain. War Office
Military records of the British Army, 1914-1920 (surnames T) Great Britain. War Office
Military records of the British Army, 1914-1920 (surnames U-Z) Great Britain. War Office
As you probably know these records only represent just a small proportion of the total Records rescued. I have it on good authority that a lot of the S's survived.
Good luck,
Pat
p.s.
Family History Main Search Page
Blue Drop down Menu select " Library Catalogue"
Title Search: Enter "British Army",
From these Titles look at the British Army Military Records, say "S"
Select this and the then upper top right corner select view film notes.
You will then get a a range of 1-100 of 3371 Burnt Records in the "S" range. ( this is the same as the ranges in the NA)
Just work your way through until you get the range that cover your soldier, for example names beginning with Sy will be towards the end of 3371.
Ask the LDS centre to get the film for you. Sometimes common names will be over a range of names, so you will need more than one film.
For your names up to "N" these are on Ancestry, but who knows when they will list the remainder.